Is this an electrical connector, a fuse, or what?

[slackmax]

In my (endless?) journey to fix my air handler, I now want to disconnect what I think is a connector.  I have it partly apart but now am wondering if it really is a connector.  A  fuse, maybe? 

See pics.   

It is the horizontal white thing just below the UL sticker.  It has 2 wires going in on the left and 2 wires going out on the right. I want to get it apart because it would be a nice place to test for voltage going to the blower motor.

Thanks.

[slackmax]

ANother angle.

[zolotiyeruki]

Connector

[slackmax]

Thanks. 

[snic]

Usually with those there's a tab somewhere to squeeze to get it to release. Sometimes you have to use a screwdriver to push a tab down.

[slackmax]

Usually with those there's a tab somewhere to squeeze to get it to release. Sometimes you have to use a screwdriver to push a tab down.

Thanks. 

There are two tabs (ears) on it. I have been pushing the rear tab away with a flathead screwdriver, while using my finger on the front tab, and pulling it out and leftward.  Awkward.  But I have it started.  Will go back and finish it off, knowing it is indeed a connector.     

[ATtiny85]

That thing in the upper right of the first picture (bunches of wires of all sizes and colors) is a contactor (what I was calling a relay in the other thread). It uses the 24V to pull in the big voltage. I have had those get clogged with spiders and dust and other crap (especially after multiple decades.

That might a something to explore. It would definitely cause the fan to not run if defective / dirty.

[slackmax]

That thing in the upper right of the first picture (bunches of wires of all sizes and colors) is a contactor (what I was calling a relay in the other thread). It uses the 24V to pull in the big voltage. I have had those get clogged with spiders and dust and other crap (especially after multiple decades.

That might a something to explore. It would definitely cause the fan to not run if defective / dirty.

Thanks. 

I did get the connector off. I stretched one of the tabs a bit, but nothing is broken, lol. There was a third thing on top of the connector that had to flip up also.

While we are on the topic, I checked voltage going to the blower motor (which won't come on) and it was only 21 volts, no matter id it was supposed to be off or on. I was expecting either zero or 120 volts. SOmething else for me to research.

[lthenderson]

I always struggle diagnosing things like that. Perhaps the only time I have ever been successful was last spring when I went to use my A/C for the first time and the fan worked but the condenser never would turn on.  After finding out it would likely be two weeks before a technician could look at it, I pulled the covers and started probing around myself. It has power everywhere but wouldn't turn on. I finally, by dumb luck, discovered the problem. Behind a panel there was a recess there a single wire came from a grommet in the sheet metal and ran into the house. Behind that sheet metal, the wire had been gnawed off by a critter and the only reason I found it was because I was trying to trace it to the place where all the other wires met up and never could find it. That wire went to the temperature sensor saying that the condenser was needed. Since it was gnawed in half, the condenser just assumed the temperature inside my house didn't need cooling. Short of testing the sensor in both conditions, which I couldn't do unless the condenser was working properly, I never would have figured it out by testing things.

[slackmax]

I always struggle diagnosing things like that. Perhaps the only time I have ever been successful was last spring when I went to use my A/C for the first time and the fan worked but the condenser never would turn on.  After finding out it would likely be two weeks before a technician could look at it, I pulled the covers and started probing around myself. It has power everywhere but wouldn't turn on. I finally, by dumb luck, discovered the problem. Behind a panel there was a recess there a single wire came from a grommet in the sheet metal and ran into the house. Behind that sheet metal, the wire had been gnawed off by a critter and the only reason I found it was because I was trying to trace it to the place where all the other wires met up and never could find it. That wire went to the temperature sensor saying that the condenser was needed. Since it was gnawed in half, the condenser just assumed the temperature inside my house didn't need cooling. Short of testing the sensor in both conditions, which I couldn't do unless the condenser was working properly, I never would have figured it out by testing things.

Well, it's almost Spring, and I won't be wanting much heat then, ha ha.

Congratulations on persevering and finding the solution to your problem. I love it when it works out that way.   

I wish these internet forums would be more helpful to me. They answer about half my questions, and just ignore the rest, even if I ask again. Frustrating, but what do ya want for free, right?

I am going to look for animal damage next.

[ATtiny85]

I always struggle diagnosing things like that. Perhaps the only time I have ever been successful was last spring when I went to use my A/C for the first time and the fan worked but the condenser never would turn on.  After finding out it would likely be two weeks before a technician could look at it, I pulled the covers and started probing around myself. It has power everywhere but wouldn't turn on. I finally, by dumb luck, discovered the problem. Behind a panel there was a recess there a single wire came from a grommet in the sheet metal and ran into the house. Behind that sheet metal, the wire had been gnawed off by a critter and the only reason I found it was because I was trying to trace it to the place where all the other wires met up and never could find it. That wire went to the temperature sensor saying that the condenser was needed. Since it was gnawed in half, the condenser just assumed the temperature inside my house didn't need cooling. Short of testing the sensor in both conditions, which I couldn't do unless the condenser was working properly, I never would have figured it out by testing things.

Well, it's almost Spring, and I won't be wanting much heat then, ha ha.

Congratulations on persevering and finding the solution to your problem. I love it when it works out that way.   

I wish these internet forums would be more helpful to me. They answer about half my questions, and just ignore the rest, even if I ask again. Frustrating, but what do ya want for free, right?

I am going to look for animal damage next.

It’s not fully clear what all steps you have taken. You need to figure out if full voltage is going to the blower fan (I don’t think that has been answered). I would be tempted to figure out the pinout on the contactor and directly jumper it. You could also post a pic of the wiring diagram and maybe we could help you.

[sonofsven]

Maybe this will help? Top ten reasons an HVAC blower motor won't turn on.
https://www.youtube.com/watch?v=kijnOOQZF2E

[slackmax]

That thing in the upper right of the first picture (bunches of wires of all sizes and colors) is a contactor (what I was calling a relay in the other thread). It uses the 24V to pull in the big voltage. I have had those get clogged with spiders and dust and other crap (especially after multiple decades.

That might a something to explore. It would definitely cause the fan to not run if defective / dirty.

I checked the contactor and it is pristine. Not even a cobweb in it.

[slackmax]

ATiny85 wrote << It’s not fully clear what all steps you have taken. You need to figure out if full voltage is going to the blower fan (I don’t think that has been answered). I would be tempted to figure out the pinout on the contactor and directly jumper it. You could also post a pic of the wiring diagram and maybe we could help you.  >>

OK, steps so far.

Replaced capacitor. Old capacitor was down to 5 microfarads, SHould have been 10.

Tested for voltage between R and G. Everything was kosher there. 28 volts when fan is not called for. Zero volts when fan is called for.

While I am on the R and G topic, I have not jumpered between them yet. Afraid of it for some reason, but will get to it eventually. Want to find out why I am only getting 21 volts to blower first. Also unclear to me whether jumpering R and G is supposed to bypass whatever the problem is and make fan come on, or what. 

***  Tested for voltage at the two wires going to blower motor. (the wires at the connector) Got 21 Volts there.  Was expecting to see zero volts or 120 volts. Maybe 21 volts is a default voltage for the blower ?  And by the way, I get 21 volts there when fan is supposed to be off, and also when it is supposed to be on. I have the voltmeter set on 700 volts, just to be safe.    ***

Fan spins freely and quietly if shoved by hand.

Looked inside control box and only see wires and a relay. No circuit board. No spider webs, etc. Nice and clean.

** Wondering if the outside unit's circuit board controls the air handler.   **

Someone said the outside unit is very unlikely to be involved in this, and I hope he is right.

Looked all over for signs of animal damage, loose wires, chafed wires, etc. Haven't found anything. Have not looked inside outside unit for cobwebs, debris etc on a circuit board or whatnot, since outside unit is not supposed to be involved.

Have assumed the thermostat is not to blame, but could be wrong.

I can try to photograph the wiring diagram, but it is small print.

For those interested, I have a previous post in this thread about the  same blower motor topic.

My main curiosity now is why I am only getting 21 volts to blower and why in both fan off, and fan on.

[slackmax]

contactor and fuses pic

[slackmax]

air handler

[ATtiny85]

***  Tested for voltage at the two wires going to blower motor. (the wires at the connector) Got 21 Volts there.  Was expecting to see zero volts or 120 volts. Maybe 21 volts is a default voltage for the blower ?  And by the way, I get 21 volts there when fan is supposed to be off, and also when it is supposed to be on. I have the voltmeter set on 700 volts, just to be safe.    ***

This seems to be the main "issue". The low voltage might just be because there is a loop back and you are picking up a backfed type voltage from the transformer. I would perhaps consider it as zero.


Did you check that thermal fuse?

The outside unit is independent of this.

If you sit staring at the relay/contactor and have the thermostat switch form off to "fan only" what happens? Jumping the Red to Green is simply putting 24Volts (Red) to the Fan wire (Green) which is the same at flipping the switch at the thermostat.

[slackmax]

***  Tested for voltage at the two wires going to blower motor. (the wires at the connector) Got 21 Volts there.  Was expecting to see zero volts or 120 volts. Maybe 21 volts is a default voltage for the blower ?  And by the way, I get 21 volts there when fan is supposed to be off, and also when it is supposed to be on. I have the voltmeter set on 700 volts, just to be safe.    ***

This seems to be the main "issue". The low voltage might just be because there is a loop back and you are picking up a backfed type voltage from the transformer. I would perhaps consider it as zero.


Did you check that thermal fuse?

The outside unit is independent of this.

If you sit staring at the relay/contactor and have the thermostat switch form off to "fan only" what happens? Jumping the Red to Green is simply putting 24Volts (Red) to the Fan wire (Green) which is the same at flipping the switch at the thermostat.

Have not checked the thermal fuses yet.

I will set the thermostat to 'off' and 'auto'. Then if I go downstairs and sit in front of the air handler and jumper  G to R, I might hear the relay click on, or the contactor, or both, right?

[slackmax]

OK, I went ahead and did it. Set thermostat to off and auto, then went down to the air handler and jumped G and R with a penny. Heard a click when I touched the penny to the terminals, and another click when I removed the penny.

The click was coming from inside the box.

The contactor didn't make any sound, or move at all.

I had multimeter probes in the wires to the motor, and the voltage was stuck at 21, even when jumping the R and G. Actually, it did move up or down, but just by one volt between jumpered an unjumpered. 

Making progress, eh ?

[ATtiny85]

You really don’t seem to be getting voltage to the motor.

You need to check that fuse.

[slackmax]

OK.  Just to make sure we are on the same page, the fuses I am talking about, in the pic, are to the right of the contactor. Two of them, a beige color, looks like Bakelite maybe. Oval triangle shape.

I will look up how to test them with a multimeter.   

Just to add some background, when the problem started, the system ran for at least a day with tons of heat from the coils, and maybe even from the aux strips, with no fan to remove it. I remember noticing the vent was warm, but no air blowing. Maybe all the heat down there tripped a fuse that needs to be 'reset'.

Anyway, yes, I will test both those fuses.

[index]

Have you priced out a new blower motor and control board? Amazon usually has free return shipping. What is the model number of your unit?

[zolotiyeruki]

On my furnace, there's a kill switch that disables the blower while the cover is open, as a safety feature.  Does yours have a similar feature?

[ATtiny85]

On my furnace, there's a kill switch that disables the blower while the cover is open, as a safety feature.  Does yours have a similar feature?

I certainly can’t see one, and the whole perimeter seems to be in that pic above.

This is a great reminder though for OP. Those normally kill all of it though, I think??

[zolotiyeruki]

On my furnace, there's a kill switch that disables the blower while the cover is open, as a safety feature.  Does yours have a similar feature?

I certainly can’t see one, and the whole perimeter seems to be in that pic above.

This is a great reminder though for OP. Those normally kill all of it though, I think??

Yeah, on mine, it kills power to the controller, and therefore to the rest of the system.

[sonofsven]

At a certain point I just start replacing the most suspect parts. Did you watch that video I linked? Did any of it connect with your issues?

[slackmax]

Have you priced out a new blower motor and control board? Amazon usually has free return shipping. What is the model number of your unit?

Yes. Blower motors range from $50 to $500.  I saw a control board for this for $65 I think, but must be for the outdoor unit.  But there is no 'board' as in pcb board, in the air handler. There is a pcb board in the outside unit, and no one seems to know if it has any control over the inside fan, although some have said that the outdoor unit is totally uninvolved in my problem (including the pcb I guess).

Of course I want to be sure that replacing a part will solve the problem, before I order it.

Just for kicks, I spent 3 hours taking the panels off my outside unit, just to look at stuff. I cleaned out some cobwebs and dead spiders from behind the pcb board, and a lot of sludge from the bottom of the unit, and shoved a grommet back in place. . The red light was flashing once per second on the pcb board, which means it is happy.     

[slackmax]

On my furnace, there's a kill switch that disables the blower while the cover is open, as a safety feature.  Does yours have a similar feature?

No. No kill switch that I noticed.

[slackmax]

At a certain point I just start replacing the most suspect parts. Did you watch that video I linked? Did any of it connect with your issues?

Yes, I watched it. Thanks. I was able to benefit from the part about testing the capacitor. My old capacitor was bad, and I replaced it, but that alone didn't fix the problem. SO I went on from there.

I'm about ready to join the mosh pit at some thrash rock show soon, lol, to unwind !!   

[slackmax]

Have you priced out a new blower motor and control board? Amazon usually has free return shipping. What is the model number of your unit?

Trane Air handler.  model number  BWV724A100E0

[slackmax]

You really don’t seem to be getting voltage to the motor.

You need to check that fuse.

There are 2 thermal fuses  there.  I took them both out and tested them today. Both good. According to the continuity test. Set my muiltimeter to 200 ohms, hooked it up to the fuse, reading went up and bounced around 35, 45, 135, and then back down and stayed low, bouncing around 0.3,  0.4,  0.5 ohms. Supposedly that means the fuses are OK. 

Put them back in. 



 

[ATtiny85]

Darn, that was going to be an easy one. Your meter should have a continuity setting, which would be better for a fuse check, though it seems like you still got to the same spot (super low resistance equals continuity…)

So, it sounds like to me that we might be all the way back to the poster on the other thread said “control board”. Occam's Razor perhaps…

I am pretty sure I would still educate myself on how to bypass everything in the control board and make the fan run. It should be a somewhat simple manner of putting 24v to the terminal of the contactor.

I know it sounds scary, but the 24v just energizes an electromagnet and makes a connection on the high voltage side.

My reasoning 1) I can make the system work, and 2) just to check that side of it. I have had two blowers go out, though they were the fancy DC multi speed design.

If someone else has an opinion, please toss it out, the OP has been quite the trooper here!

[slackmax]

Darn, that was going to be an easy one. Your meter should have a continuity setting, which would be better for a fuse check, though it seems like you still got to the same spot (super low resistance equals continuity…)

So, it sounds like to me that we might be all the way back to the poster on the other thread said “control board”. Occam's Razor perhaps…

I am pretty sure I would still educate myself on how to bypass everything in the control board and make the fan run. It should be a somewhat simple manner of putting 24v to the terminal of the contactor.

I know it sounds scary, but the 24v just energizes an electromagnet and makes a connection on the high voltage side.

My reasoning 1) I can make the system work, and 2) just to check that side of it. I have had two blowers go out, though they were the fancy DC multi speed design.

If someone else has an opinion, please toss it out, the OP has been quite the trooper here!

Yes, I am fighting the good fight, lol. Luckily I have the spare time to do it.

By the way I was able to get a 120 volt reading at one of the wires going to the motor.   It was upstream from the motor, at a connector I opened up. 2 wires on the connector on one side. Got 120 volts at one wire and zero at the other wire. Seems encouraging.

I agree that it would be ideal to get 120 volts to the motor to see if it comes on.

Or just verify that there is 120 volts at one of the 2 wires that immediately attach to the motor terminal, when fan is supposed to be on.

Still wondering why the motor spins so easily, if it is bad, but apparently that can happen, if the windings have shorted out. 

Another idea is doing the OHM test on the motor, which I will get to eventually, no doubt.

[zolotiyeruki]

Darn, that was going to be an easy one. Your meter should have a continuity setting, which would be better for a fuse check, though it seems like you still got to the same spot (super low resistance equals continuity…)

So, it sounds like to me that we might be all the way back to the poster on the other thread said “control board”. Occam's Razor perhaps…

I am pretty sure I would still educate myself on how to bypass everything in the control board and make the fan run. It should be a somewhat simple manner of putting 24v to the terminal of the contactor.

I know it sounds scary, but the 24v just energizes an electromagnet and makes a connection on the high voltage side.

My reasoning 1) I can make the system work, and 2) just to check that side of it. I have had two blowers go out, though they were the fancy DC multi speed design.

Agreed on the suggestion to apply 24v (AC!) to the coil of the contactor.  If the blower spins up, that'll rule out both the contactor and the motor (and the wiring in between) as the fault.

The wiring diagram that's on the air handler will prove immensely helpful.  Can you post a good quality photo of it?

Still wondering why the motor spins so easily, if it is bad, but apparently that can happen, if the windings have shorted out. 

Another idea is doing the OHM test on the motor, which I will get to eventually, no doubt.

An AC induction motor will spin freely when no power is applied to it, assuming the bearings are good and nothing is blocking it. A winding failure will not make it harder to spin.

Checking the resistance of the windings is a good idea.  You'll want to unplug the wires from the control board, so they're only connected to the motor.  Measure the resistance between the white wire and the various other wires.  If any of them show an open circuit, there's your problem. You *can* temporarily swap these colored wires (but not the white one!) around while testing--supplying power to various wires makes the motor spin at various speeds.  One wire at a time, though! :)

I'm not 100% convinced the "contactor" is that.  Can you post a closeup photo of that?  I have to wonder if it's a thermal breaker, and the lack of finer-gauge wire (it's all heavier-duty stuff) makes me think it's a different type of switch.  It's wired up to something above it that may be a thermal breaker.

[ATtiny85]

I'm not 100% convinced the "contactor" is that.  Can you post a closeup photo of that?  I have to wonder if it's a thermal breaker, and the lack of finer-gauge wire (it's all heavier-duty stuff) makes me think it's a different type of switch.  It's wired up to something above it that may be a thermal breaker.

Yeah, I agree with your potential disagreement with my first identification. Somewhere (of course) there is a switch controlled by the 24VAC (thanks for the reminder to be more specific) that puts voltage to the blower motor. Looking at the earlier pictures I can't quite tell what is going from the lower control box to that upper area. (there's a green wire I lose) What should be up there are the thermal fuses (maybe one for hot, one for cold) and something else. Looking around the web, I see various thermal switches, but nothing that looks exact. Not sure if there is a pressure switch of any sort on these types of units.

Looking at one of the pics in the original thread, it sure seems like the wiring diagram it readable for OP, so maybe a pic would be possible.

[zolotiyeruki]

I'm not 100% convinced the "contactor" is that.  Can you post a closeup photo of that?  I have to wonder if it's a thermal breaker, and the lack of finer-gauge wire (it's all heavier-duty stuff) makes me think it's a different type of switch.  It's wired up to something above it that may be a thermal breaker.

Yeah, I agree with your potential disagreement with my first identification. Somewhere (of course) there is a switch controlled by the 24VAC (thanks for the reminder to be more specific) that puts voltage to the blower motor. Looking at the earlier pictures I can't quite tell what is going from the lower control box to that upper area. (there's a green wire I lose) What should be up there are the thermal fuses (maybe one for hot, one for cold) and something else. Looking around the web, I see various thermal switches, but nothing that looks exact. Not sure if there is a pressure switch of any sort on these types of units.

Looking at one of the pics in the original thread, it sure seems like the wiring diagram it readable for OP, so maybe a pic would be possible.

On my furnace, it's a relay on the control board that sends 120VAC to the blower motor.  There's no separate contactor.  And typically, aren't contactors used for far larger electrical equipment?

I don't know if there's an airflow sensor for the air handler, but there might be.  On my furnace, there's an air pressure sensor on the induction blower, to confirm that combustion air is flowing before it'll turn on the gas and ignite the burners.  Apparently, it's fairly sensitive, too--several years ago, a 1" wasp nest in a 2" vent pipe blocked enough air flow to prevent the furnace from turning on.

[slackmax]

schematic. Unreadable? Maybe the symbols will show up.

[slackmax]

Thermal fuses and 'contactor'. When I took the thermal fuses out, I saw they had little resistor type objects sticking into the airway.

[zolotiyeruki]

schematic. Unreadable? Maybe the symbols will show up.

Yeah, the wiring diagram didn't come through clear enough.  Any chance you can try again?

[ATtiny85]

Wait!

Where is the electric strip heat back-up? Are we seeing that in that "top" area? I totally forgot about that feature.

(that would explain my confusion on what is up and is down in that jumble or wires)

2nd edit: yeah, that whole thing is the electric heat.

We need to return again to the control board. OP heard what seems like the control relay click somewhere in these threads.

[slackmax]

A better view. More to come.

[slackmax]

schematic 2

[slackmax]

schematic 3

[slackmax]

schematic 4

[index]

Turn on the power and connect (wire nut) 1 and 3 off the fan motor relay and you take everything out of the equation I think from reading that diagram. Power is going straight to the fan at that point.  Thoughts?

[ATtiny85]

Turn on the power and connect (wire nut) 1 and 3 off the fan motor relay and you take everything out of the equation I think from reading that diagram. Power is going straight to the fan at that point.  Thoughts?

Yeah, that is the "1" and "3" in the Fan Relay, labeled "F" in the lower middle. This is likely in the lower left box on the pic way up top.

Index also meant turn OFF the power, connect those two wires, then turn on power and call for fan (or heat, whatever)


This will at least take the blower motor in or out of this discussion.

[slackmax]

OK, I am to open up the control box, find the fan relay, which has five wires attached to it and take off the back two wires ( 1 and 3, both of which are red), join them together, turn power on and call for fan, hoping for fan to come on. Correct?   

[ATtiny85]

Yeah, that’s what we would do…

[zolotiyeruki]

OK, I am to open up the control box, find the fan relay, which has five wires attached to it and take off the back two wires ( 1 and 3, both of which are red), join them together, turn power on and call for fan, hoping for fan to come on. Correct?

As I read it, you won't need to call for fan.  You'll be hooking the motor straight up to AC power, bypassing anything that could switch it off (other than the thermal fuses, etc at the top).  If the blower spins, that means that the blower relay has failed.  You can either replace the board, or you can exercise some soldering skills to remove the failed relay from the board and replace it.

The wiring diagram doesn't seem to include all the thermal stuff at the top, although there's a portion of the diagram on the right-hand side that we can't see yet.  What I *can* see indicates that there's a second blower, probably an induction blower?  If you could send a photo of the right hand of the wiring diagram, that may shed additional light.

[ATtiny85]

There shouldn’t be an induction blower here, it’s a heat pump. That other wiring area must be for a different model version.

Good call on not needing to call for fan, I was clearly not thinking things through. Thanks, it’s little things like that that be confusing for the poor soul on the other end of these troubleshooting blasts.